A tuna is a saltwater finfish that belongs
to the tribe Thunnini, a sub-grouping of
the mackerel family (Scombridae),
which includes the bonito(Sardini) and mackerel (Scombrini) tribes. Thunnini comprises fifteen species across five genera,[1] the sizes of which vary greatly, ranging from thebullet tuna (max.
length: 50 cm (1.6 ft), weight: 1.8 kg (4.0 lb)) up to the Atlantic
bluefin tuna (max. length: 458 cm (15.03 ft),
weight: 684 kg (1,510 lb); the bluefin averages 200 cm
(6.6 ft), and is believed to live for up to 50 years.
Their circulatory and respiratory systems
are unique among fish, enabling them to maintain a body temperature slightly
higher than the surrounding water. An active and agile predator, the tuna has a
sleek, streamlined body, and is among the fastest-swimming pelagic fish – the yellowfin tuna,
for example, is capable of speeds of up to 75 km/h (47 mph).[2] Found in warm seas, it is extensively fished commercially
and is popular as a game fish. As a result of over-fishing, stocks of some tuna
species have been reduced dangerously close to the point of extinction.
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